Defines +,- for Triangular matrices

Fix #5927
Windows: download busybox-win32 during make win-extras

copy it to echo.exe and printf.exe during make dist
This allows test/spawn.jl to succeed on Windows, since echo and printf
are only included as shell scripts in msysgit (and an echo.bat in
contrib/windows), but libuv cannot spawn shell or bat scripts.
Fix #7551

Simply drop out of search mode (back to the original mode) when accepting an empty search-string.
distinguish between libraries and bundled exe's
Support for icc and ifort.
It is possible to use MKL's FFT through their FFTW wrappers
Clean up compiler warnings
Use rem_pio2 from openspecfun. Allows other libms to be used again.
Fix #5365
Rename USE_MKL -> USE_INTEL_MKL and add deprecation
Introduce USE_INTEL_MKL_FFT
Disable dsp and fft tests that are not supported by MKL's fftw wrappers
Merge pull request #7547 from JuliaLang/vs/icc

WIP: Compile julia with icc and ifort
Enable filtering (filt) across columns of arrays

When passed a multidimensional array, simply iterate over its columns, independently filtering each one.  The starting filter state may be given as a vector (in which case it is common across all columns) or an array with the same number of columns as the input.
Relax filt signatures to allow heterogeneous types

Previously, filt[!] methods were only defined for arguments of all the same type T<:Number. This relaxes that restriction, allowing one to, for example, filter an array of Float32s by Float64 coefficients.

By default, the output of filt will be the determined by promote_type of all arguments.

Instead of defining many type parameters (T<:Number, S<:Number, ...), filt now simply trusts that the eltype of the arrays have methods for basic arithmetic.
Fix deprecation for Triangular(::Matrix)
Bump openspecfun

fix exporting of Faddeeva and amos functions from libopenspecfun.dll
Bump openspecfun
Merge branch 'master' of github.com:JuliaLang/julia
Merge pull request #7446 from tkelman/busybox

Windows: download busybox-win32 during make win-extras
Remove outdated size tweak from performance tips section of manual
Merge branch 'master' of github.com:JuliaLang/julia
API change to fix the type instability

Because we're back to only one optional element for both `filt` and `filt!` (the initial state), I figure it's simpler to just use a positional argument in both cases.  So now the API is:

    filt(b, a, x, [si])
    filt!(out, b, a, x, [si])
Merge pull request #7560 from mbauman/filtarray

Filtering (filt) across columns of arrays and method signature tweaks
Cartesian: preserve {} when the argument can't be reduced to a number